Nickel Cobalt Separation via Non-Saponification Extraction
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Solution Overview
Problem
Current methods for separating nickel and cobalt from solutions using acidic extractants lead to increased hydrogen ion concentration, requiring saponification with costly reagents like NaOH or ammonia water, resulting in wastewater pollution and high treatment costs.
Innovation Solution
A method involving acidic and alkaline extractants, such as 2-ethylhexyl dihydrogen phosphate and tri-octyl decyl amine, is used to separate nickel and cobalt without saponification, adjusting the pH to 3.5-4.5, and using a volume ratio of 2-4:6-8 for the extractants, with kerosene as a diluent, to effectively extract cobalt into the organic phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic extractants are used for nickel-cobalt separation, then extraction efficiency is improved, but hydrogen ion concentration increases causing acid leaching enhancement and affecting extraction effect
Solution Approach 1:
The patent introduces a buffer solution as an intermediary substance to mediate between the acidic extractant and the aqueous phase. The buffer solution absorbs excess hydrogen ions released during extraction, preventing acid leaching enhancement while maintaining extraction efficiency. This resolves the contradiction by adding a mediating component that controls the harmful effect without compromising the beneficial extraction process.
2Reliability
If saponification with NaOH is performed to replace hydrogen ions, then extraction effect is maintained, but treatment cost increases and salt content in wastewater exceeds standard
Solution Approach 1:
The patent replaces expensive NaOH saponification with a cost-effective buffer solution system. The buffer solution, composed of inexpensive components like ammonium acetate or sodium acetate, neutralizes acid without requiring costly alkaline saponification. This substitutes a cheap, disposable buffering mechanism for an expensive treatment process, reducing treatment costs while maintaining extraction reliability.
Solution Approach 2:
The patent converts the harmful effect of hydrogen ion accumulation into a beneficial control mechanism by using buffer solutions. Instead of viewing increased acidity as purely harmful, the system utilizes controlled buffering to maintain optimal pH ranges for extraction. This transforms the acid-generation issue into a manageable parameter, converting a harmful effect into a controllable and even beneficial aspect of the extraction process.
3Ease of manufacture
If concentrated ammonia water is used for saponification, then cost is reduced, but ammonia nitrogen content in wastewater increases causing serious waterbody pollution
Solution Approach 1:
The patent replaces ammonia water saponification with buffer solutions based on acetates or other non-polluting salts. These buffer systems neutralize acid without introducing ammonia nitrogen into the wastewater. The cheap buffering agents serve as disposable neutralizing agents that eliminate pollution concerns while maintaining cost-effectiveness, resolving the contradiction between low treatment cost and environmental pollution.
4Reliability
If saponification procedure is performed, then hydrogen ions are replaced, but process complexity increases and wastewater discharge amount increases
Solution Approach 1:
The patent merges the pH control function and extraction function into a single integrated buffer-extraction system. Instead of separate saponification and extraction steps, the buffer solution is present throughout the extraction process, simultaneously maintaining pH stability and enabling extraction. This consolidation eliminates the need for separate saponification procedures, reducing process complexity while maintaining extraction stability.
Solution Approach 2:
The patent implements continuous pH control through buffer solutions that actively maintain optimal pH levels throughout the entire extraction process. Rather than periodic saponification interruptions, the buffer provides continuous neutralization of hydrogen ions, ensuring stable extraction conditions without process interruptions. This continuous action maintains reliability while simplifying the overall process by eliminating discrete saponification steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This non-saponification method efficiently separates nickel and cobalt, reducing wastewater discharge and operational costs, while maintaining effective extraction efficiency under acidic conditions.
Implementation Method 1
adding extractants for extraction to separate nickel from cobalt, wherein the cobalt enters the organic phase, and the nickel remains in the aqueous phase
Implementation Method 2
The extractants contain an acidic extractant and an alkaline extractant... the cobalt enters the organic phase
Data Source
AI summary
A method for separating nickel and cobalt from a solution includes the steps of: obtaining a solution containing nickel and cobalt by acid leaching of a cathode material of a waste lithium-ion battery, adjusting the pH of the solution containing nickel and cobalt to 3.5 to 4.5, adding extractants for extraction to separate the nickel and the cobalt. The cobalt enters the organic phase, the nickel remains in the aqueous phase, and the extractants contain an acidic extractant and an alkaline extractant. The method for efficiently separating nickel and cobalt through extraction adopts a non-saponification extraction method without using NaOH as a saponifier, thereby avoiding the discharge of saponification wastewater. Under acidic conditions, the cobalt in an acidic leaching solution is effectively extracted and separated into the organic phase through synergistic action of the acidic extractant and the alkaline extractant, thereby realizing the separation of nickel from cobalt.